Thiomalates of alkaline earth metals

Solid state 1:1 complexes of divalent Mg, Ca, Sr and Ba with thiomalic acid(tma) have been isolated and characterised by elemental analysis, IR spectra and thermal studies. It is shown that tma coordinates to the metal ions through carboxylic oxygen atoms. Thermal studies of these complexes show that desulphurisation preceeds decarbonylation reaction leading to the formation of metal carbonates in all the cases except Mg where MgO is the end product. Thermal stability of the anhydrous thiomaltes follows the order Mg ∼ Ca > Sr > Ba. Structures have been proposed based on the information obtained from these studies.     

Synthesis of a diazacrown ether containing polymers and formation of complexes with alkaline earth metals

We report the synthesis of a polymer that contains the diaza‐18‐crown‐6 moiety on the polymer main chain. Metal containing polymers were obtained when the respective barium or strontium complexes were used as monomers. These polymers emitted greenish blue light in solution, and the metal had little influence on absorption and emission energies. In the solid state, the position of the emission peaks was different probably due to a different degree of aggregation.     

Reactions of alkaline earth metal or al slurries with bis-cyclopentadienyl complexes of some early transition metals

Slurries of Mg, Ca, Ba and Al, prepared by cocondensation of metal vapour with volatile organic solvents, especially toluene, at –196°C, reacted at ambient temperature with some bis-cyclopentadienyl complexes of Ti, Zr, Hf, V and Cr. [TiCl₂Cp₂] (Cp = η⁵-C₅H₅) with slurries Al in hexane or toluene, or Mg or Ba, in toluene, formed [TiClCp₂]₂ accompanied by side-products. From related reactions with slurries of Mg in tetrahydrofuran (THF), [TiCl₂Cp(THF)] was obtained and with Ca-toluene slurries an unstable paramagnetic dihydrido complex of Ti(III) was observed by using ESR spectroscopy. Reactions of [TiPh₂Cp₂ with slurries of Al or Ba in toluene yielded a form of “titanocene” (TiC₁₀H₁₀) and ESR studies of these reactions revealed related paramagnetic species in solution. Reaction of slurries of Al, Mg or Ba with [TiMe₂Cp₂] produced several different paramagnetic products which were studied by ESR spectroscopy, and the reaction of metal slurries with the complexes [MR₂Cp₂] (M = Ti, R = OPh; M = Zr or Hf, R = Cl or Me), [VRCp₂] (R = Cl or Me), and [CrCp₂] are also reported.     

Ethylene oligomerization on heterogenized titanium and zirconium complexes

Besides other products, linear middle-range olefins were obtained in the low temperature oligomerization of ethylene with a selectivity of 30–58% and a linearity up to 85%. Activated ticanium and zirconium complexes as catalysts were attached to SiO₂ through surface bounded bidentate S- and N-containing ligands, the former being superior to the latter with respect to product quality.

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30–58 .% 85%. - - , , SiO₂ S- N- . , , .

     

Ion chromatographic determination of alkaline earth metals and some heavy metals

The method is described for ion chromatographic determination of Ba, Ca, Cd, Cu, Mn, Ni, Sr, Pb and Zn. Ethylenediammonium chloride or tartrate solutions are used as eluents with a suppressor column. The detection limits for the listed elements are (in μg l^?1): Ba 1.4, Ca 0.045, Cd 0.6, Cu 0.3, Mn 0.8, Ni 0.5, Pb 6.3, Sr 0.3, Zn 1.2. Relative standard deviations are 0.015–0.050 ar the 20 mg l^?1 level (n = 5, p = 0.95). Interferences are considered.     

Study of the alkaline earth metals with 8-hydroxyquinolinate derivatives

Metal complexes of calcium with 5,7-dibromo, 7-iodo and 5-chloro-7-iodo-8-hydroxyquinolate were precipitated in aqueous ammonia and acetone medium, except for the solid state compound with 5,7-dichloro-8-hydroxyquinoline which hasn"t been obtained under these conditions. The complexes obtained through the mentioned precipitation are Ca[(C₉H₄ONBr₂)₂]₃·H₂O, Ca[(C₉H₅ONI)₂]·2H₂O and Ca[(C₉H₄ONICl)₂]·2.5H₂O. Their intermediate from the thermal decomposition found through TG/DTA curves in air indicated the presence of different kinds of calcium carbonates related to the reversibility and crystalline structure, depending on the original compounds. The initial compounds and the intermediate from the thermal decomposition were also characterized through IR spectra and X-ray diffraction. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and characterization of titanium and zirconium complexes with silicone-bridged phenoxycyclopentadienyl ligands

Dimethylsilyl(2,3,4,5-tetramethylcyclopentadienyl)(3-tert-butyl-5-methyl-2-phenoxy)titanium dichloride (1a), a useful catalyst precursor for olefin copolymerization, was synthesized at high yield starting from allyl-protected phenolic ligand 3a,which was first treated with 2 equiv. of n-BuLi to selectively give the dilithium salt of 3a along with 1-heptene, a coupling product of a protected allyl ether moiety and butyl anion. Addition of TiCl₄ to the resulting dilithium salt of 3a in toluene afforded 1a in 50% isolated yield. This methodology could be applied to the preparation of related titanium and zirconoium complexes 1b-1d, 8 with silicone-bridged Cp-phenoxy ligands, whereas the reaction starting from methyl-protected precursor 2a did not produce the zirconium complex 8. Copolymerization of ethylene and 1-hexene with the newly prepared complexes was also investigated.     

Structural investigation of Eu emissions from alkaline earth zirconium phosphate

Eu²⁺ doped A_0.5Zr₂(PO₄)₃ (A=Ca, Sr, Ba) phosphors with the NASICON structure were synthesized by a co-precipitation method. Their photoluminescent and structural properties were investigated by photoluminescent spectroscopy and powder X-ray Rietveld analysis, which determined two sites for Eu²⁺ ions in the host structure, 3a and 3b. The Eu-O bond lengths were increased by changing alkaline earth ions from Ca to Ba, causing Eu²⁺ emission bands to shift from blue-green to blue. A correlation was observed between the peak wavelength positions and the Eu-O bond length. The photoluminescent properties are discussed in terms of crystal field strength and nephelauxetic effect, and a schematic diagram of Eu²⁺ emissions is proposed for the Eu²⁺ doped NASICON phosphor.     

Catalytic dehydrogenation of cyclooctane with titanium, zirconium and hafnium metallocene complexes

Metallocene complexes in combination with cocatalysts like methylalumoxane (MAO) are not only excellent catalysts for olefin polymerization but also appropriate catalysts for the activation of alkanes in homogeneous (autoclave) and heterogeneous (fixed bed reactor) reactions. The activities of the catalysts depend on the temperature, the cocatalysts, additives, the central metal and the ligand structure. Generally, complexes with low steric demands and MAO as cocatalyst gave the highest activities. The comparison of different π-ligands resulted in the following activity order: cyclopentadienyl > indenyl > fluorenyl. The influence of σ-ligands and n-donor ligands gave the following activity order: -Cl > -PMe₃ > -CH₂Ph > -(CH₂)₄CH₃ > -NPh₃. The activities depended on the nature of the cocatalyst and decreased in the following order: MAO ? AlMe₃ > AlEt₃. The addition of aluminum powder and the Lewis base NPh₃ increased the activity of the Cp₂ZrCl₂/MAO catalyst. The Cp₂ZrCl₂/MAO/NPh₃ catalyst showed the highest activity in homogeneous reactions with 458 turnovers in 16 h at 300 °C. The Cp₂ZrCl₂/MAO/NPh₃/SI1102 catalyst gave the highest activity in heterogeneous catalysis with 206 turnovers in 5 h at 350 °C. None of the catalysts required a hydrogen acceptor like an external olefin.     

Lithium, titanium, and zirconium complexes with novel amidinate scorpionate ligands

The reaction of bis(3,5-dimethylpyrazol-1-yl)methane (bdmpzm) with BunLi and carbodiimide derivatives, namely, N,N'-diisopropyl, dicyclohexyl, and 1-tert-butyl-3-ethyl carbodiimides, enables the preparation of new heteroscorpionate ligands in the form of the lithium derivatives [Li(NNN)(THF)] (NNN = pbpamd (1) (pbpamd = N,N'-diisopropylbis(3,5-dimethylpyrazol-1-yl)acetamidinate); cbpamd (2) (cbpamd = N,N'-dicyclohexylbis(3,5-dimethylpyrazol-1-yl)acetamidinate); and tbpamd (3) (tbpamd = N-ethyl-N'-tert-butylbis(3,5-dimethylpyrazol-1-yl)acetamidinate)), although a similar process with N,N'-dimethylcarbodiimide gave the dinuclear complex [Li(bpzii)(THF)]2 (4) (bpzii = N-(dimethylamino)-N'-[(dimethylamino)bis(3,5-dimethylpyrazol-1-yl)methylimino]imino). When this last reaction was carried out in an air atmosphere, the cluster complex [Li8(mu4-O)2(mu4-OH)2(mu4-pz)2(kappa2-bpziLi)2(bpzCN)2(THF)4] (5) (bpziLi = dimethylaminobis(3,5-dimethylpyrazol-1-yl)methyliminolithium, bpzCN = bis(3,5-dimethylpyrazol-1-yl)acetonitrile) was isolated and characterized by X-ray analysis. Finally, when the same process was carried out in the presence of water the amidine-scorpionate (bpzan) (6) (bpzan = N,N-dimethylbis(3,5-dimethylpyrazol-1-yl)acetamidine) was obtained. Compounds 1 and 3 reacted with [TiCl4(THF)2] or [ZrCl4] to give complexes of stoichiometry [MCl3((kappa3-NNN))] (M = Ti, Zr) (7-10). The structures of the different compounds were determined by spectroscopic methods and, in addition, the X-ray crystal structures of 1, 3, 4, 5, and 6 were also established.     

Ring‐opening polymerization of cyclic esters by pincer complexes derived from alkaline earth metals

We report the synthesis and characterization of new Ca(II) and Mg(II) complexes of the type [Ph―PPP]MR (M = Ca, R = N(SiMe₃)₂ ( 1 ); M = Mg, R = ⁿBu ( 2 )) where Ph―PPP^? is a tridentate monoanionic ligand (Ph―PPP―H = bis(2‐diphenylphosphinophenyl)phosphine). Reaction of the opportune metal precursor (Ca[N(SiMe₃)₂]₂.THF₂ or MgⁿBu₂) with 1 equiv. of the pro‐ligand Ph―PPP_―H produces the corresponding calcium amido ( 1 ) or magnesium butyl ( 2 ) complex in high yield. Solution NMR studies show monomeric and kinetically stable structures for both species. The obtained complexes efficiently mediate the ring‐opening polymerization of ?‐caprolactone showing a turnover frequency of 40 000 h^?1. In the presence of a hexogen alcohol, up to 2000 equiv. of monomer are converted by using a low loading of catalyst (5 µmol). Kinetic studies show a first‐order reaction in monomer concentration. Copyright © 2014 John Wiley & Sons, Ltd.     

Neutral all metal aromatic half-sandwich complexes between alkaline earth and transition metals: an ab initio exploration

Structural Chemistry - Sandwich complexes find their interests among the chemists after the breakthrough discovery of ferrocene. Since then, a number of sandwich and half-sandwich complexes were...     

Helical ternary complexes of alkaline earth picrates with open-chain crown ether

Much attention has been paid to the amide-type open-chain crown ethers with versatile mo-lecular structures because of their characteristic physical and chemical properties. These types of ligands have been used successfully as the active materials for ion-selective electrodes and the extractants for metal ions[1—5]. Among these ligands, N,N,N′,N′-tetraphenyl-3,6,9-trioxaun- decanediamide (TTD) shows the high extractabilities for Sr2+, Ba2+ and rare earth ions and the good selectivity to…     

Synthesis and structural variations of substituted phenylamide complexes of the heavy alkaline earth metals calcium, strontium and barium

Starting material KN(H)C(6)H(3)-2,6-F(2) was prepared via a transamination reaction from KNH(2) and 2,6-F(2)C(6)H(3)NH(2) in THF and crystallized from 1,4-dioxane (diox) as the three-dimensional polymer [(diox)(1.5)K{N(H)-2,6-F(2)C(6)H(3)}.diox(0.5)](infinity) (1). The metathesis reaction of (THF)(4)CaI(2) with KN(Me)Ph in THF yields monomeric (THF)(4)Ca[N(Me)Ph](2) (2) with a nearly linear N-Ca-N moiety of 179.84(8) degrees . The metathesis reaction of (THF)(4)CaI(2) with KN(H)Mes yields trinuclear (THF)(6)Ca(3)[N(H)Mes](6) (3) with a linear Ca(3) fragment and bridging 2,4,6-trimethylphenylamido groups. The reaction of 1 with (THF)(4)CaI(2) gives dinuclear (THF)(5)Ca(2)[N(H)-2,6-F(2)C(6)H(3)](4).2THF (4) with three bridging and one terminally bound 2,6-difluorophenylamide. A similar reaction of (THF)(5)SrI(2) with KN(H)-2,6-F(2)C(6)H(3) yields dinuclear (THF)(6)Sr(2)[N(H)-2,6-F(2)C(6)H(3)](3)I.THF (5) in which the iodide anion binds terminally. This iodide ligand cannot be substituted as easily by excess KN(H)-2,6-F(2)C(6)H(3). The metathesis reaction of (THF)(5)BaI(2) with KN(H)-2,6-F(2)C(6)H(3) leads to the formation of [(THF)(2)Ba{N(H)-2,6-F(2)C(6)H(3)}(2)](infinity) (6) which crystallizes as a one-dimensional polymer with bridging 2,6-difluorophenylamide anions and additional Ba-F-bonds.     

Carbalumination of higher α-olefins catalyzed by titanium and zirconium complexes

Conclusions A regioselective method was developed for the carbometallation of higher-olefins using Et₃Al and Et₂AlCl in the presence of titanium and zirconium complexes which permits the preparation of higher trialkylaluminums and dialkylaluminum halides in high yield under mild conditions in one step.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 207–209, January, 1985.